The present invention relates generally to wall fasteners of the type generally referred to as Molly bolts that are used on dry wall and the like. More particularly, a removable hollow-wall anchor having a detachable head is described.
Hollow-wall anchors (or Molly bolts) are typically used in dry wall such as sheet rock. Molly bolts are used where screws or nails will not work, for example in sheet rock where there is no solid surface for the screw or nail to bite into. Once the Molly bolt is affixed to the wall, objects can then be attached to the outside surface of the wall using the Molly bolt. A screw, nail, or bolt by itself would not hold in dry wall.
A Molly bolt is composed of two separate parts, an anchor and a machine screw. The anchor incorporates the threads, a number of deformable legs (usually three or four) and a head. The head functions much like the head of a nail to prevent the Molly bolt from entering the wall; it also has tangs which enter the wall and prevent the anchor from rotating when the machine screw is threaded in.
A Molly bolt comes with the machine screw already threaded into and fully inserted into the anchor. Once the Molly bolt is hammered into the dry wall, the screw is turned as if to thread it into the anchor. However, as the screw is already fully inserted into the anchor, the threaded portion of the anchor is pulled towards the wall, thus deforming the legs and pressing them up against the inside of the wall. The anchor of the Molly bolt is thus permanently secured to the wall. The screw can then be removed and reinserted to hold an object to the wall.
It should be apparent that it is critical to the operation of the Molly bolt that the anchor not rotate while the screw is turned. If the anchor were to turn, the legs would not be pulled up against the inside of the wall. Thus, the tangs on the head of the Molly bolt serve the important function of digging into the wall and preventing the rotation of the anchor.
One disadvantage of the Molly bolt is that it is permanently fixed to the wall. Once the tangs of the head dig into the outer surface of the wall and the deformed legs press tight against the inner surface of the wall, the anchor is permanently in place. As the anchor is all one piece, the wall must be partially destroyed in order to remove the Molly bolt.
Considering the above disadvantages of traditional Molly bolts, a Molly bolt that is removable from a wall once affixed would be desirable.